Mercuric reductase is an essential component in the mercury detoxification in a number of bacteria. It catalyzes the two electron reduction from Hg(II) to Hg(0). The homo-dimeric protein requires NADPH and FAD for catalysis. In addition to these cofactors, four cysteine residues have been identified in the active site and shown to play a key role in mercury binding and reduction. One of the specific goals of my work is to define these two steps in molecular detail. The structural information available from X-ray crystallography and accessible through MidasPlus has proven very useful for the design of experiments. Furthermore, the data I have obtained using UV/VIS and fluorescence spectroscopy in combination with static and rapid kinetic techniques are surprisingly complex. The interpretation of these data strongly relies on additional structural information; namely, the spatial arrangement of the four cysteines in the mercuric ion binding site. The resources available at the Computer Graphics Laboratory are invaluable.